Device enabling operatin of portable equipment in a severe environment

ABSTRACT

The device according to the invention comprises a box ( 1 ) lined on the inside with an insulating coating ( 2 ) and containing a pack ( 3 ) filled with an exothermal crystallization reaction mix ( 4 ).  
     The elements to be heated ( 5 ) such as CD-ROMs, batteries, etc. are located inside the box. These elements can operate satisfactorily after having been heated in this box, when they are subjected to very low temperatures (for example −40° C.).

[0001] This invention relates to a device enabling operation of portable equipment in a severe environment.

[0002] When equipment is designed to operate in severe environments such as environments applicable to military, aeronautical or space equipment, these types of equipment are made according to much stricter standards than those applicable to standard equipment, consumer equipment or “COTS” (“Commercial off the Shelf”) equipment, thus making this special equipment much more expensive than standard equipment. The current trend is to reduce the cost of such special equipment by using “COTS” equipment, after being selected and possibly adapted to stricter standards.

[0003] This type of equipment designed to operate in severe environments must in particular be capable of operating correctly at negative temperatures, for example down to −40° C., which is particularly the case for military equipment but is not the case for lots of “COTS” equipment. Standard equipment that does not resist this type of constraint includes electrical power supply batteries and computer peripherals such as CD-ROM, DVD-ROM drives, diskette drives, PCMCIA drives, Flash memory readers. Their operation is usually guaranteed only at temperatures above 0° C., and their published technical characteristics do not mention their behaviour below 0° C.

[0004] Furthermore, after long-term cold storage, the media read by the drives concerned need to be heated before being inserted in the drives to prevent condensation problems and various malfunctions. The operation of batteries used in this type of equipment required to operate in a severe environment are severely degraded during cold weather: they have a very short endurance and it is practically impossible to charge them.

[0005] In order to solve these problems, a heating device is used for these elements sensitive to cold. However, electrical heating devices consume a great deal of energy, so that they are not suitable for portable appliances for which endurance is a very important criterion. Heating devices making use of fuel are also unsuitable due to the many disadvantages of the fuel (dangerous, bulky, difficult to regulate, etc.). Heating devices containing a mix of liquid and salts that can be crystallized under the effect of a shockwave producing an exothermal reaction, are also known. Although these devices do not need any energy source to produce heat, they are not suitable for use in a severe environment due to their fragility.

[0006] The purpose of this invention is a device enabling operation of equipment in a severe environment, particularly of portable electronic equipment, comprising elements for which operation is degraded or impossible at low temperatures (significantly below 0° C.), a device that does not reduce the endurance of equipment or appliances controlled by it, and that is simple, lightweight and inexpensive to make.

[0007] The device according to the invention comprises a protective box in which the inside surface is coated with a thermal insulation, and which contains at least one pack containing a mix subject to an exothermal crystallization reaction with its device to trigger the reaction under the effect of a shockwave controllable from outside the box, with the elements to be heated placed inside the box.

[0008] This invention will be better understood after reading the detailed description of an embodiment used as a non-limitative example and illustrated in the attached drawing in which the single FIGURE is a simplified sectional view of an example embodiment of a device according to the invention.

[0009] The invention is described below with reference to heating an electrical power supply battery for a portable electronic device, and a compact disk such as a CD-ROM, but obviously it is not restricted to heating these elements (and/or maintaining their normal operating temperature), and it can be used for other types of portable or non-portable elements and/or appliances, either during storage, immediately before use or during use, or even after use. For example, these elements and appliances may include computer peripherals (CD-ROM drive, DVD-ROM drive, diskette drive, “flash” memory readers, etc.), of complete portable appliances (micro-computers, radio telecommunication or GSM sets, measurement instruments, etc.).

[0010] The device according to the invention uses a heating device previously used for consumer type appliances (baby bottle warmer, dish warmer, massage appliances, etc.). This heating device is in the form of a sealed pack made of a flexible plastic material containing a mix of water and salts with exothermal properties. The mix is in liquid form at normal ambient temperature and it changes to the solid state at a certain negative temperature that depends on the chemical composition of the mix. When the temperature to which this mix is subjected exceeds this solidification value, all that is necessary to trigger a chain reaction causing creation of crystals throughout the complete mix is to create a shockwave in the mix. The shockwave acts as a catalyst for the solidification reaction that is exothermal. The released heat is released over a period of 30 min to 2 hours or even more, depending on the composition of the mix and heat losses. The temperature may increase to +50° C. Once the mix has completely solidified, it has to be heated to a temperature of about +100° C. to reactivate it, in other words to liquefy it so that another exothermal reaction can be triggered. The advantage of this type of “passive” heating device is that it releases heat energy without any energy consumption, and therefore without reducing the endurance of the appliances that it is required to heat in the device according to the invention. The only phase during which this heating device consumes energy is when it is being recharged to liquefy the solidified mix. However, this phase can be done external to the mission during which the heating device is to be used, in a location (laboratory, deposit, workshop, plant, etc.) in which energy sources with unlimited endurance are available. Obviously, if the mission in question is to last more than about two hours, several heating devices can be provided that will be used in sequence.

[0011] When the elements to be heated in the device according to the invention have been heated, they can be kept at the required temperature (which is not necessarily their normal operating temperature for an ambient temperature of about 20° C., but which is preferably simply more than 0° C.), by their self-heating and/or self-heating of the equipment of which they form part or in which they are included. However, if this self-heating is insufficient, the device according to the invention can provide additional heat for these elements. Obviously, in this case, if some elements will not operate unless they are inserted in their equipment, the dimensions of the box will be selected so that this equipment containing the elements to be heated can also fit into it (for example a CD-ROM drive which is then connected to its microcomputer through an appropriate cable, or a GSM station power supply battery which is then connected to this station through an appropriate cable). Thus if necessary, the equipment containing elements that need to be heated when the ambient temperature is strongly negative, may be slightly modified and connected by a cable (or any other appropriate link) to these elements or a subset of this equipment that receives or contains these elements.

[0012] The single FIGURE shows a drawing of an example embodiment of the device according to the invention. This device comprises a protective box 1 in which the useful area is coated with a coat 2 of thermal insulation. A flexible reservoir 3 is fixed inside this box containing a mix 4 of the type mentioned above with an exothermal solidification reaction. The reservoir 3 is placed in the box 1 so as to leave the maximum possible amount of space available for the elements to be heated. In the example shown in the drawing, the reservoir 3 is in the form of a pack coating the inside surface of four consecutive walls of the box 2 (in other words all walls except for the two walls forming the front and the back of the box), the wall forming the front of the box being removable or tipping so that the elements 5 to be heated can be put into the box. In the example shown on the drawing, these elements are a CD-ROM and a battery, but obviously the device according to the invention could be used to heat many other elements such as those mentioned above. The reservoir 3 is fitted with a shockwave trigger device 6 in which a control handle 7 passes through a wall of the box in a sealed manner and can therefore be manipulated from the outside. This device 6 is usually a metallic dish that can be bent at its centre producing a sudden break. However, other similar devices may be used.

[0013] According to one alternative of the invention, two or more distinct reservoirs with an exothermal mix are placed inside the box 1, in order to increase the duration of heating by the device according to the invention. Thus, when the amount of heat produced by the first used reservoir starts to reduce, the next reservoir is triggered and so on if there are several such reservoirs. Obviously, each reservoir is provided with its own trigger device.

[0014] Thus using the device according to the invention, it is possible to operate several items of electronic equipment at very low ambient temperature (−40° C. or even less) without reducing the endurance of this type of equipment, and in a severe environment (presence of sand, dust, chemical contaminants, blunt objects, infrared and ultraviolet radiation, etc.), due to the fact that the box containing the heating device includes a compartment that can easily be made leak tight and resistant to shocks, radiation and various pollutants. Obviously, in this case, the portable equipment itself must be designed to be at least as strong as the heating device compartment. This heating device contains the quantity of the exothermal reaction mix (possibly in several independent packs used one after the other) necessary to provide sufficient heating for portable equipment even for relatively long missions (several hours) in a very cold environment. 

1. Device for operation of portable devices in a severe environment, characterised in that it comprises a protective box (1), in which the inside surface is coated with a thermal insulation (2) and in which at least one pack (3) containing an exothermal crystallization reaction mix (4) with its device (6) for triggering the reaction by shockwave (7) controllable from outside the box, the elements to be heated (5) being located inside the box.
 2. Device according to claim 1, characterised in that the box is made leak tight and/or of a material resistant to shocks and/or a material resistant to chemical contaminants and/or a material resistant to IR and UV radiation.
 3. Device according to claim 1 or 2, characterised in that the elements to be heated are connected to equipment with which they cooperate and are heated during their common operation.
 4. Device according to claim 3, characterized in that the elements to be heated are placed in the box with sub-assemblies of portable devices necessary for operation of these elements.
 5. Device according to one of the previous claims, characterised in that it comprises several independent packs, each containing a mix and used in turn. 